1. Field of the Invention
The invention relates to the field of electrocoagulation, and in particular to the use of alternating currents to form endovascular occlusions.
2. Description of the Prior Art
Occlusion of vascular structures by endovascular catheters is currently realized though the use of detachable balloons, injectable glue, detachable or pushable coils, and injectable particles. Detachable balloons are of such a nature that they can only be practically used in large vessels. The use of injectable glue is limited by the difficulty of controllable delivery to the desired occlusion site. Detachable and pushable coils are effective, but in some cases are not sufficiently thrombogenic. The use of injectable particles suffers from their relative invisibility in fluoroscopy and the difficulty in controlling their ultimate disposition at the desired occlusion site. In many prior art technologies the coagulation wire must be ripped out of the clot, usually causing considerable disruption or even reopening the occlusion.
The use of both alternating and direct current for creating electrocoagulation is well known. See, Gold et al., "Transarterial Electrocoagulation Therapy of a Pseudoaneurysm in the Head of the Pancreas, " American Journal of Roentgenology, Volume 125, No. 2, at 422 (1975); Thompson et al., "Vessel Occlusion with Transcatheter Electrocoagulation: Initial Clinical Experience, " Diagnostic Radiology at 335 (November 1979); Thompson et al., "Transcatheter Electrocoagulation: A Therapeutic Angiographic Technique for Vessel Occlusion, " Investigative Radiology at 146 (March-April 1977); Phillips, "Transcatheter Electrocoagulation of Blood Vessels, " Investigative Radiology at 295 (September-October 1973); and Phillips et al., "Experimental Closure of Ateriovenous Fistula by Transcatheter Electrocoagulation," Diagnostic Radiology 115:319 (May 1975). However, each of these experimental investigations were generally performed in larger vessels and did not establish controllability, nor efficacy for use in smaller vessels.
Therefore, what is needed is a clinical occlusive device which is visible, biocompatible, controllable in that it can be detached at will at a desired site even distal to the delivery microcatheter, which is directable, efficacious in coagulating blood and vessel and usable in small vessels without the risk of causing disruption or reopening the occlusion at the end of the treatment.